For many years, electronic systems (i.e., computers, printers, etc.) have been designed with one or more printed circuit boards (PCBs) that are electrically connected together to perform various functions. One of these printed circuit boards, which is commonly employed within computers, is referred to as a “motherboard”. The motherboard typically is the main printed circuit board that provides interconnections between primary electronic components of the computer such as its processor, memory, and the like.
Businesses may follow a well-established circuit board assembly procedure in order to manufacture a fully functional circuit board. This circuit board assembly procedure may have four sequential stages of which the second, third and fourth stages are performed in an assembly line environment while the first stage is performed beforehand, normally at an off-line site, in an effort to speed up the assembly line stages. The first stage may involve programming various programmable electronic components using well-known manual or automated equipment operated by one or more persons. These programmable electronic components include, but are not limited to, read-only memory (“ROM”), erasable programmable read-only memory (“EPROM”) and electrically erasable and re-programmable non-volatile memory (typically referred to as “flash” memory). Afterwards, electronic components are connected to the circuit board during the second or third stages.
The second and third stages involve assembly of the circuit board by connecting surface mount technology (“SMT”) components followed by through hole mount technology (“THMT”) components through various widely known techniques. For example, the technique for connecting SMT components to the circuit board may include the following operations: (i) solder paste application, (ii) proper placement of the SMT components, and (iii) reflow soldering to establish connections between trace lines previously routed in the circuit board and the SMT components. Likewise, the technique for connecting the THMT components may include the following operations: (i) proper placement of THMT components, and (ii) wave soldering.
The fourth stage in manufacturing circuit boards may involve testing each component (i.e., “in circuit” testing) as well as the entire operation of the circuit board (i.e., “functional” testing) to determine whether the circuit board is functioning properly.
Assembly of the circuit board may involve overhanging components such as connectors, sockets, components and the like on leading or lagging edges of the PCBs. Overhanging surface mount technology (SMT) components are a challenge to assemble in the SMT board assembly process. Overhanging components may be devices that extend outward past the edge of a printed circuit assembly (PCA). Overhanging components may require a large “stay out” area to not interfere with SMT assembly tools such as screen print and placement machines. As such, design rules may include “stay out” zones that prohibit overhanging components on leading and/or lagging edges of PCAs. The leading and lagging edges are the non-conveying edges of the PCA. However, the SMT equipment “stay out” zone for overhanging devices may vary for different types of tools (i.e., chip shooter, component placer, screen printer) and may vary for different placement equipment vendors. The stay out zones may vary so much from different types of tools and suppliers that design rules may require that the entire leading edge of the PCA is a “stay out” zone for overhanging SMT components. More specifically, the board stops, tooling pins and sensors may be located in different areas on the equipment.